Turning PDF pages into images is one of those tasks with an obvious first step and a non-obvious second one. The first step is choosing the tool. The second is choosing between JPG and PNG, and getting it wrong is why exported pages sometimes come out looking slightly dirty around the text.
The decision is genuinely simple once you know what each format was designed for.
Two formats, two different jobs
JPG is for photographs
JPEG compression works by throwing information away — specifically, fine detail that human vision is poor at noticing. It looks at small blocks of the image, keeps the broad shapes and discards subtle variation.
On a photograph this is close to magic. A landscape can lose 90% of its data and look essentially unchanged, because the eye was never tracking the exact value of each pixel in a patch of sky.
PNG is for everything with hard edges
PNG compression is lossless. It finds patterns and repetition and encodes them compactly, and what comes out is bit-for-bit what went in. That works brilliantly on images with large areas of flat colour and sharp boundaries — text, line drawings, charts, screenshots, logos — which is exactly the content JPEG handles worst.
The failure mode is visible and specific. Around every sharp edge, JPEG leaves a faint halo of noise, because a hard black-to-white transition is precisely the "fine detail" the algorithm assumes it can approximate. On a page of body text, that means every letter sits in a small cloud of grey speckle. Zoomed out it looks like slight blurriness; at 100% it looks like dirt.
The rule
Ask one question: is the page mostly text, or mostly photograph?
- A contract, a report page, an invoice, a form, a slide with bullet points, a page with charts or tables — export as PNG. Text stays crisp.
- A full-page photograph, a scanned photo, a magazine page that is mostly imagery — export as JPG. Much smaller, and the loss is invisible.
- Mixed pages, when in doubt — PNG. The file is bigger, but nothing is degraded, and you can always convert down later. You cannot convert back up.
That last point is the one worth internalising: JPEG loss is permanent. Every save discards a little more. Keep PNG as the archival copy and generate JPGs from it as needed.
Resolution matters more than format
Before either format gets involved, the page has to be rendered into pixels, and the scale you choose at that moment sets the ceiling on quality. Get this wrong and no format choice will save you.
Useful reference points for an A4 or Letter page:
- 72–96 DPI (roughly 600–800 px wide) — thumbnails and previews only. Body text will not be readable.
- 150 DPI (about 1,240 px wide) — comfortable on screen, fine for a slide or a web page.
- 300 DPI (about 2,480 px wide) — print quality, and the right choice if the image will be re-printed or if someone needs to read small print.
- 600 DPI — archival scanning of fine detail. Large files; rarely necessary.
The usual mistake is exporting at screen resolution and then discovering the image is needed at print size. Rendering again from the PDF is free, so err upward.
Transparency
PNG supports an alpha channel; JPEG does not. If you are exporting a logo, a diagram or a signature to place on top of something else, PNG is the only one of the two that can give you a transparent background. A JPEG will always arrive with a solid rectangle behind it — usually white, occasionally an unwelcome black.
What about file size, really?
For a typical text page at 150 DPI, expect the PNG to be somewhere between two and five times the size of an equivalent JPG. That sounds decisive until you look at the absolute numbers: a few hundred kilobytes against maybe a hundred. If you are exporting three pages for a presentation, the difference does not matter and the quality does.
Where it does matter is bulk. Exporting 400 pages at 300 DPI as PNG will produce a very large folder, and that is a reasonable moment to reach for JPG on the pages that are photographic.
A quick decision list
- Mostly text or line art → PNG.
- Mostly photographic → JPG.
- Need a transparent background → PNG, no alternative.
- Will be printed → 300 DPI, and PNG unless the page is a photograph.
- Hundreds of pages and size is the constraint → JPG, but check one text-heavy page at 100% zoom before committing to the whole batch.
Doing it without uploading
Rendering pages is computation your device is perfectly capable of. Both tools draw each page onto a canvas in your browser and encode the result locally, so a 200-page document never gets copied to a server and you are not waiting on an upload before anything happens. Large exports arrive as a single archive so you are not clicking through hundreds of downloads.
In short
PNG for text and diagrams, JPG for photographs, PNG when unsure, and pick your resolution before you pick your format — because resolution is the part you cannot fix afterwards without going back to the PDF.